Method for Efficient Database Formation and Search on Media Devices Acting Synchronously with Television Programming

ABSTRACT

Techniques for efficient database formation and search in applications embedded in a media device are provided. The search may be performed synchronously with presentation of media programming content on a nearby media presentation device. A mobile media device captures some temporal fragments of the presented audio/video content on its microphone and camera, and then generates query fingerprints for the captured fragment. A local reference database resides on the mobile media device and a master reference database resides on a remote server with a most recent chunk of reference fingerprints transferred dynamically to the local mobile media device. A chunk of the query fingerprints generated locally on the mobile media device are searched on the local reference database for continuous content search and identification. The method presented automatically switches between the local search on the mobile media device and a remote search on an external search server.

This application claims the benefit of U.S. patent application Ser. No.13/826,502 filed Mar. 14, 2013 which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/610,672 entitled “A Methodfor Efficient Data Base Formation and Search on Portable Media DevicesActing Synchronously with Television Programming” filed on Mar. 14, 2012which are hereby incorporated by reference in their entirety.

CROSS REFERENCE TO RELATED APPLICATIONS

U.S. application Ser. No. 12/141,337 filed on Jun. 18, 2009 entitled“Method and Apparatus for Multi-dimensional Content Search and VideoIdentification”, U.S. application Ser. No. 12/141,163 filed on Jun. 18,2008 entitled “Methods and Apparatus for Providing a ScalableIdentification of Digital Video Sequences” now issued as U.S. Pat. No.8,229,227, U.S. application Ser. No. 12/141,337 filed on Jun. 18, 2008entitled “Method and Apparatus for Multi-Dimensional Content Search andVideo Identification” now issued as U.S. Pat. No. 8,171,030, U.S.application Ser. No. 12/788,796 filed on May 24, 2010 entitled“Multi-Media Content Identification Using Multi-Level Content SignatureCorrelation and Fast Similarity Search”, U.S. application Ser. No.12/772,566 filed on May 3, 2010 entitled “Media Fingerprinting andIdentification System” now issued as U.S. Pat. No. 8,195,689, U.S.application Ser. No. 12/612,729 filed on Nov. 5, 2009 entitled “DigitalVideo Content Fingerprinting Based on Scale Invariant Interest RegionDetection with an Array of Anisotropic Filters” now issued as U.S. Pat.No. 8,189,945, U.S. Pat. No. 8,229,227 filed on Jun. 18, 2008 entitled“Methods and Apparatus for Providing a Scalable Identification ofDigital Video Sequences”, U.S. patent application Ser. No. 13/094,158filed on Apr. 26, 2011 entitled “Actionable Event Detection for EnhancedTelevision Delivery and Ad Monitoring Based on Video/Audio ContentFingerprinting”, U.S. Provisional Patent Application Ser. No. 61/610,672filed on Mar. 14, 2012 entitled “A Method for Efficient Data BaseFormation and Search on Portable Media Devices Acting Synchronously withTelevision Programming”, and U.S. patent application Ser. No. 13/509,701filed on Aug. 21, 2012 entitled “Media Content Identification On MobileDevices” and having the same assignee as the present application arerelated applications and hereby incorporated by reference in theirentirety.

FIELD OF THE INVENTION

The present invention relates generally to aspects of efficientidentification of audio or video media, such as television programming,by using a media device equipped with audio/video signal capturing andfingerprinting mechanisms. More particularly, it relates to aspects ofrobust audio/video signal fingerprinting in the presence of ambientnoise, efficient database formation distributed between a remote serverand the media device, and database query with automatic switchingbetween remote search on an external search server and local search on alocal reference database on the media device.

BACKGROUND OF THE INVENTION

With the ubiquity of mobile devices, especially smart mobile phones, alarge proportion of the population often simultaneously watchprogramming content on their television while using their portablemobile device for text messaging or Internet related activities. Recentdevelopment of audio/video content fingerprinting technologies andcapable mobile/media devices as smart phones and tablets, have opened upmany new possibilities in developing sophisticated applicationssynchronous to detected television programming events. However,techniques for identifying captured segments of media presented on adevice such as a television have proven to be very difficult to achieve.

SUMMARY OF THE INVENTION

Among its several aspects, the present invention recognizes it ispossible to have efficient video synchronous applications on a mediadevice by providing the media device with capability to promptlyidentify and track content being played on a television set in thepresence of ambient noise.

In one or more of its several aspects, the invention addresses problemsof efficient media device local data base structuring, and query resultbased switching between query search on the local reference data baseand the query search on the remote server reference data base. Anembodiment of the invention addresses a method for efficiently queryinga database on a media device. A reference cache database is formed onthe media device partitioned for multiple levels of query search,wherein each search level represents a larger portion of the referencecache database than a previous search level. Each search level isqueried in progressively larger portions of the reference cache databaseon the media device with automatic switching between a local search onthe media device and a remote search on an external search database uponnot finding a match in any search level portion of the reference cachedatabase. Upon finding a match in the remote search, a chunk ofreference media content fingerprints is downloaded from a neighborhoodof matching reference fingerprints on the external search database to bestored in the reference cache database on the media device, whereby thereference cache database is updated with current search area referencematerial.

Another embodiment addresses a method for simultaneous capture andquerying on a mobile media device. A first fragment of media content iscaptured from a media presentation device during background operationson a mobile media device, wherein the captured first fragment of mediacontent is saved to a circular buffer. The first fragment of capturedmedia content retrieved from the circular buffer is fingerprinted togenerate signatures representing the first fragment of captured mediacontent. A local reference database on the mobile media device isqueried with the generated signatures while a second fragment of mediacontent is being captured from the media presentation device.

Another embodiment addresses a method for manual and automatic localsignature cache management. A signature cache is formed on a mobilemedia device to hold one set of signatures that is automatically managedfor switching between a local search and a remote search, whereindownloading of reference media signatures and signature cache managementare performed automatically based on search responses from the localsearch and from the remote search. A manually managed signature cache isformed with functions provided that allow for explicit downloading ofthe reference media signatures to the signature cache.

A further embodiment addresses a computer readable non-transitory mediumencoded with computer readable program data and code. A reference cachedatabase is formed on the media device partitioned for multiple levelsof query search, wherein each search level represents a larger portionof the reference cache database than a previous search level. Eachsearch level is queried in progressively larger portions of thereference cache database on the media device with automatic programcontrolled switching between a local search on the media device and aremote search on an external search database upon not finding a match inany search level portion of the reference cache database. Upon finding amatch in the remote search, a chunk of reference media contentfingerprints is downloaded from a neighborhood of matching referencefingerprints on the external search database to be stored in thereference cache database on the media device, whereby the referencecache database is updated with current search area reference material.

A more complete understanding of the present invention, as well asfurther features and advantages of the invention, will be apparent fromthe following Detailed Description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system for providing audio and video synchronoustwo-screen applications on a media device;

FIG. 2 illustrates a process for television content audio/video captureon a media device;

FIG. 3 illustrates a process to identify video and audio contentcaptured by a mobile media device from a nearby television (TV) screenand to trigger a mobile application action on the mobile media device;

FIG. 4 illustrates a process to automatically switch between a searchoperation on a remote search server and a local search operation on amobile media device;

FIG. 5 illustrates a plurality of search levels available to a mobilemedia device;

FIG. 6 illustrates a process for a mobile media device initiated localor remote query search utilizing a miss counter;

FIG. 7A illustrates a process for a mobile media device initiated localquery search utilizing a miss counter; and

FIG. 7B illustrates a process for controlling and limiting access to aremote server to prevent increase in the network bandwidth for the caseof a query for nonexistent reference data in a remote referencedatabase.

DETAILED DESCRIPTION

The present invention will now be described more fully with reference tothe accompanying drawings, in which several embodiments of the inventionare shown. This invention may, however, be embodied in various forms andshould not be construed as being limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of theinvention to those skilled in the art.

It will be appreciated that the present disclosure may be embodied asmethods, systems, or computer program products. Accordingly, the presentinventive concepts disclosed herein may take the form of a hardwareembodiment, a software embodiment or an embodiment combining softwareand hardware aspects. Furthermore, the present inventive conceptsdisclosed herein may take the form of a computer program product on acomputer readable storage medium having non-transitory computer usableprogram code embodied in the medium. Any suitable non-transitorycomputer readable medium may be utilized including hard disks, CD-ROMs,optical storage devices, flash memories, or magnetic storage devices.

Computer program code or software programs that are operated upon or forcarrying out operations according to the teachings of the invention maybe written in a high level programming language such as C, C++, JAVA®,Smalltalk, JavaScript®, Visual Basic®, TSQL, Perl, use of .NET™Framework, Visual Studio® or in various other programming languages.Software programs may also be written directly in a native assemblerlanguage for a target processor. A native assembler program usesinstruction mnemonic representations of machine level binaryinstructions. Program code or computer readable medium as used hereinrefers to code whose format is understandable by a processor. Softwareembodiments of the disclosure do not depend upon their implementationwith a particular programming language.

The methods described in connection with the embodiments disclosedherein may be embodied directly in hardware, in a software moduleexecuted by a processor, or in a combination of the two. A softwaremodule may reside in RAM memory, flash memory, ROM memory, EPROM memory,EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or anyother form of storage medium known in the art. A computer readablestorage medium may be coupled to the processor through local connectionssuch that the processor can read information from, and write informationto, the storage medium or through network connections such that theprocessor can download information from or upload information to thestorage medium. In the alternative, the storage medium may be integralto the processor.

One aspect of the invention presents a method to identify media contentwhich includes audio, video, or both audio and video content, bycapturing the audio and/or video data from the mobile device,appropriately processing the audio and/or video content, fingerprintingthe audio and/or video data, and searching fingerprint databases toidentify the audio or the video content. Captured fragments of audio,video, or audio and video signals are hereinafter referred to as mediacontent. FIG. 1 illustrates a system 100 for providing audio and videosynchronous two screen applications on a media device. The system 100includes a media presentation device 104, such as a television set, adesktop, laptop, or tablet computer, a digital video disc (DVD) player,or a smartphone device configured to display media programming, such astelevision programs, movies, Internet videos, or the like, or play audiomedia such as wireless received radio signals, compact discs (CDs), orthe like. The media presentation device, such as a television set, maybe connected to a remote media broadcast system 105 for receivingtelevision programming content. Also, the media presentation device 104may or may not be connected to the Internet 106. The system 100 alsoincludes a remote content identification system 108 and a mobile mediadevice 110 connected over the Internet 106 to the remote contentidentification system 108. The mobile media device 110 includes asmartphone device, a laptop, a tablet computer, or the like. Set topboxes and gaming machines may also act as a media device that is placedintermediate between an external search server and the mobile mediadevice 110, having a remote database that is a subset of an externalsearch server database but of greater capacity than a local referencedatabase on the mobile media device 110. Connections 112, 114, and 116may be wired or cabled connections, wireless connections, or acombination of wire cable and wireless connections. For example, themobile media device 110 may connect wirelessly to the Internet 106through a wireless router or over 3G or 4G networks while the remotecontent identification system 108 may be wire or cable attached througha modem to the Internet 106. The mobile media device 110 may beconfigured to acquire audio signals from the media presentation device104 by use of a microphone. The mobile media device 110 may also beconfigured to acquire images or a video from the media presentationdevice 104 by use of an image sensor or camera, such as a charge coupleddevice (CCD) image sensor and a camera lens assembly included in themobile media device 110.

Illustrated system 100 supports applications on the mobile media device110 that operate in real time and in accordance with television or othermedia programming content that is being presented on a mediapresentation device 104 and received by the mobile media device 110. Themobile media device 110 is configured to acquire a temporal fragment ofmedia content, including audio content, video content, or both, that areplaying on the media presentation device 104, using the mobile device'smicrophone, camera, or both, and generates query fingerprints from thetemporal fragment of the acquired media content.

A chunk of the query fingerprints is a set of the query fingerprintscorresponding to a time segment of the query media signal. Also, adigest of the chunk of the query fingerprints may be formulated as asearch query to a local search database on the mobile media device 110or transmitted to the remote content identification system 108, alsoreferred to as an external search database or a remote search server108, for content identification. A digest of the query fingerprints is asummarization of the fingerprints generated for the acquired mediacontent. If the search query is found in a reference database eitherlocal or remote, the search process responds with responsive data, suchas a title and timing information of the identified media content, alongwith related metadata, and sends the title, the timing information, andthe related metadata to the application that initiated the query on themobile media device 110. The original chunk of query referencefingerprints or the digest of the query fingerprints found on the remotesearch server 108 is stored on the mobile media device 110 for furtheruse in local querying a mobile media device database located on themobile media device 110 and tracking of media content. The methodpresented automatically switches between remote search on an externalsearch server, and local search on a local reference database on themobile media device. The local reference database is also described as asignature cache.

The mobile media device 110 may be configured to continuously listen,observe, or listen and observe the media programming content. Theprogramming content may also be tracked by querying locally storedmobile media device reference content. If a change in the mediaprogramming content is detected, the mobile media device 110 generatesone or more new queries that are searched for content identification.This process continues as long as the mobile media device 110 islistening to, and or observing video, or both with respect to the mediaprogramming content.

The mobile media device 110 may be equipped with an actionable programevent detection system, which generates an action signal upon detectionof a particular audio, video, or audio and video fragment stored in thereference fingerprint database. A software application running on themobile media device 110 can then perform actions based on local searchresults, presenting to the user a variety of additional information onthe same mobile media device 110 in real time while the remote mediaprogramming is still playing the associated media content.

The method presented automatically switches between a remote search onthe external search database 108, and a local search on a “micro searchserver” on the mobile media device 110.

FIG. 2 illustrates a process 200 for media content capture on a mobilemedia device. By using such a content identification system, it ispossible to configure a real-time media content analysis softwareapplication, to run on the mobile media device itself. In particular,FIG. 2 illustrates the process 200 configured to acquire playedtelevision media content from a television device 204 on a media device206. The television device 204 is configured to play a televisionprogram that generates sounds and speech from speakers in synchronismwith images and video from a display device, such as a liquid crystaldisplay (LCD) or light emitting diode (LED) display. The media device206 is configured with a microphone 208 to acquire the sounds and speechand transform the sounds and speech to audio signals. The media device206 is also configured with a camera device 210 that acquires the imagesand video, and transforms the images and video to a sequence of pixelsor frames of pixels. The media device 206 is configured with a centralprocessing unit (CPU) system 212 that acquires the audio and pixel datafor analysis.

FIG. 3 illustrates a process 300 for identification of audio or videocontent captured by a mobile device from a nearby television (TV) setand triggering a mobile application action. At step 304, a televisionprogram is selected to be played on the television set. At step 306, afragment of audio and video signals are acquired on the mobile device,such as described in U.S. Pat. No. 8,189,945 and U.S. patent applicationSer. No. 13/509,701 which are incorporated by reference in theirentirety. Audio and video signatures used for query formation areusually captured in 5-10 second chunks, either automatically in presetintervals, for example every 3 seconds, if a continuous mode ofcapturing is selected, or at a user's discretion, if the mobile mediadevice operates in an asynchronous media content capturing mode. Forexample, a user knowing a certain program is to be recorded or watched,explicitly selects a package of information, such as from a menu ofselections or from a remote web site, concerning the certain program tobe downloaded to the user's personal media device, such as a smartphoneor a tablet. The package of information contains fingerprints pertinentto the certain program and metadata containing the selected informationwith the pertinent fingerprints stored to a signature cache on theuser's personal media device.

The captured 5-10 seconds of audio and video contents are passed to theassociated step in the mobile application for processing the audio andvideo signals as an audio waveform and video frames, respectively, andto form multi-signature queries for television content identification.At step 308, the audio waveform is framed. At step 310, the framed audiowaveform is fingerprinted with an audio fingerprinting system, such asdescribed in U.S. patent application Ser. No. 13/509,701. At step 312,one or more active regions are determined in the video frames and a setof frames are selected for further processing. At step 314, activetelevision regions in the selected video frames are fingerprinted with avideo fingerprinting system, such as described in U.S. Pat. No.8,189,945. This fingerprinting may occur entirely locally on the mobiledevice, entirely remotely on a remote server, or partially locally andremotely. If performed entirely remotely, the audio waveform and thevideo frames are transmitted to the remote server. Alternatively, somepartial fingerprint processing may be done locally and then theremainder of the fingerprint processing may be done remotely. In thisalternative embodiment, video frame selection from a sequence of videoframes is performed locally on the mobile device and then only theselected video frames are transmitted to the remote server forfingerprint processing. For audio, the audio waveform may be resampledto a lower sampling rate and down mixed to one channel, beforegenerating the fingerprints. Compression of the video frame and theaudio samples may be used to reduce transmission costs.

At step 320, the audio fingerprints and video fingerprints are combinedand a selected set of fingerprints are used as query fingerprints.Having both audio fingerprints and video fingerprints representing thetelevision programming content increases the reliability of televisioncontent identification under severe audio and video signal degradationsdue to the surrounding ambient conditions. The resulting audio and videoquery fingerprints are transmitted to a search server. A search functionmay be either local, residing on the mobile media device or remote,accessed for example through the Internet cloud. At step 320, the searchserver responds with a message that details where the audio and videocontent were found in the search database, and if found, the title ofthe content, the matching times, and related metadata, like an imagerepresenting the program, details about actors, or the like. If a matchis not found at step 322, the process 300 returns to step 306 to selectanother fragment of media content for processing. If a match is found atstep 322, the process 300 proceeds to step 324.

At step 324, the mobile application receives the match data and may beconfigured to trigger actions that are based on this data, such asdescribed in U.S. patent application Ser. No. 13/094,158. Such actionsmay include displaying the identity of the content to the user,retrieving related information based on the identity of the content,allowing the user to register or “check-in” to that piece of contentwith a registration server online, display an interactive ad based onthe content and perhaps knowledge about the user, or may enable avariety of other real time applications based on detected audio andvideo content.

FIG. 4 illustrates a process 400 to automatically switch between asearch operation on a remote search server and a local search operationon a mobile media device to provide an integrated local-remote search.The client mobile/media device software library is accessed through aset of application programming interfaces (APIs). For example, at step404, a search media application initializes the mobile media device 110,a mobile media content identification library located on the mobilemedia device 110, and a remote content identification library to use thesearch media application. For example, an initialize databaseapplication programming interface (API) is utilized to initialize alocal micro search server and a remote database search server. At step406, a record and identify application is called and the search mediaapplication determines to identify ambient media content being watchedon a display device, such as a television, in response to an input suchas provided by a user of the mobile media device. The input may also beprovided by a signal supplied by an external source. The media content,or at least a fragment of the media content, may also be recorded on themobile media device for identification purposes. The record and identifyapplication is used to provide this function which communicates with thelocal micro search server, or the remote search server, or both duringthe search process.

At step 408, the media is captured and a media query is generated forthe captured media, which includes audio fingerprints, videofingerprints, or audio and video fingerprints. At step 410, the mediaquery is routed initially to the local micro search server and if themedia query is not located in the local database, the media query istransmitted to a remote search server if authorized to do so. At step412, a determination is made whether the local match was successful. Ifthe local match was successful, the process 400 proceeds to step 414. Atstep 414, a tracking application is initialized and executed to trackthe matched media content.

Returning to step 412, if the local match was not successful, theprocess 400 proceeds to step 416. At step 416, the media query istransmitted to the remote search server. At step 418, a determination ismade whether the remote search server found a match. If a match wasfound, the process 400 proceeds to step 420. At step 420, a chunk ofreference signatures for the matched media content is downloaded to themobile media device. The process 400 then returns to step 408 to processanother media query.

Returning to step 418, if a match was not found, the process 400proceeds to step 424. At step 424, the media content associated with themedia query is marked as not found in current remote search database. Atstep 426, a decision to continue search and tracking is requested. Ifthe decision is to continue search and tracking, the process 400proceeds to step 408. If the decision is to not continue search andtracking, the process 400 proceeds to step 428. At step 428, the searchmedia application calls for de-initialization when it no longer needs touse the library.

The record and identify application at step 406 performs theidentification of the content by activating step 408. There are threemain sub-functions inside this function including, media capture, suchas audio fragments, for example, 5-10 seconds of the televisionprogramming audio, media fingerprinting, such as audio fingerprintingforming multi-signature 5-10 second queries, and query referencedatabase search. In a similar manner, the record and identifyapplication may capture video segments, and generate video fingerprints,and control video search operations. For example, captured audio samplesare fed to a fingerprinting system, which computes a set of signatures.These signatures are used in the query to the search system. The queryfunction implements automatic routing of the signatures to either thelocal or the remote search system.

FIG. 5 illustrates a plurality of search levels 500 available to amobile media device. Four exemplary levels of search 502, 504, 506, and508 through which a query can progress are shown in FIG. 5. Each levelrepresents a progressively larger portion of the reference fingerprintdatabase. A query tracking level 502 has a reference search range thatis limited to a media portion adjacent to a previous successful searchmatch and just slightly larger in time span than a query length. If aprevious successful search is not available, the search process proceedsto the next search level and if necessary continuing up to executing thesearch on a remote server. With a successful remote search, acorresponding chunk of signatures for the matched data is downloaded tothe mobile media device for future reference. This level 502 is thefastest possible search option. A query +/−1 minute level 504 has areference search range that is limited to the time span around theprevious successful search match, plus or minus N seconds, with thedefault being N=60 seconds and user modifiable. A query local fulldatabase level 506 has a reference search range that is the entirelocally accessible set of reference signatures that have been downloadedto the mobile media device, which operates as a client to the remotesearch server. A query remote level 508 has a reference search range ofthe full capacity of a master reference database located on the remotesearch server. At this level 508, the media query is redirected to theremote server. This level 508 is the slowest search option due primarilyto network delays.

FIG. 6 illustrates a process 600 for a mobile media device initiatedlocal or remote query search utilizing a miss counter. FIG. 6 shows amore detailed process for the remote-local query search operation. Atstep 604, a recorded query is first sent to the local search. At step606, a determination is made whether a match is found locally. If amatch is not found in the local search, then the process 600 proceeds tostep 608. At step 608, an internal counter having a count T1 of thesearch misses is incremented. At step 610, a determination is madewhether the count value of this counter is greater than a firstthreshold, threshold1. If the count value T1 is greater than thethreshold1, the process 600 proceeds to step 612. At step 612, the queryis sent for a remote search. At step 614, a determination is madewhether a match is found from the remote search. If a match is foundfrom the remote search, the process 600 proceeds to step 616. Also,returning to step 606, if a match is found in the local search, then theprocess 600 proceeds to step 616. At step 616, the search miss counteris reset. At step 618, the found result including an indication FOUNDtogether with associated data are returned, and a chunk of referencesignatures corresponding to a range around the match point, according toa time stamp from the query, are downloaded to the mobile media device,replacing the existing local reference database with the new chunk ofsignatures, and the process 600 returns to step 604. Returning to step614, if a match is not found from the remote search, the process 600proceeds to step 620. At step 620, the originally submitted query ismarked NOT FOUND, which may be displayed or modified before displayingto a user of the mobile media device. The process 600 then proceeds tostep 604 to repeat a local search with a newly recorded query.

FIG. 7A illustrates a process 700 for a mobile media device initiatedlocal query search utilizing a miss counter. At step 704, the media isrecorded, and initial query is searched in a first subset of the fulllocal database, such as the query tracking level 502. At step 706, adetermination is made whether a match to the query has been found. If amatch is found, the process 700 proceeds to step 705. At step 705 thematch search results are obtained from the subset of the full localdatabase, such as from the query tracking level 502. The process 700then returns to step 704. If a match is not found, the process 700proceeds to step 708. At step 708, the query is searched in an extendedsubset of the full local database, such as the query +/−1 minute level504. The extended subset has larger capacity than the first subset andas a consequence takes longer to search than the first subset. The localsearch at steps 704 and 708 are fast as compared to a full localdatabase search or a reference database search at the remote searchserver. At step 710, a determination is made whether a match to thequery has been found. If a match is not found, the process 700 proceedsto step 712. At step 712, an internal counter having a count T2 of thesearch misses is incremented. At step 714, a determination is madewhether the count value T2 of this counter is greater than a secondthreshold, threshold2. If the count value T2 is not greater than thethreshold2, then the process 700 goes to step 704 to capture new queryand proceed with local search. If the count value T2 is greater thanthreshold2, then process 700 sends the query to a full local databasesearch stage as level 506. At step 716, a search of the full localdatabase is initiated. At step 718, a determination is made whether amatch has been found in the full local database. If a match is found instep 718, the process 700 proceeds to step 720. At step 720, the searchmiss counter is reset. At step 722, the match search results areobtained from the full local database on the mobile media device. Theprocess 700 then returns to step 704.

Returning to step 718, if the full local database match is not found,the process 700 proceeds to step 724. At step 724, the miss counterhaving a count T1 is incremented. At step 726, if the count value T1 ofthe miss counter is greater than the threshold1 the process 700 proceedsto do a search on a remote search server at step 728. If at step 726 thecount value T1 of the miss counter is less than the threshold1, theprocess 700 goes back to step 704.

A signature cache is a part of the mobile media device local operatingmemory dynamically allocated by the application at run time. Thesignature cache can hold at least one chunk of reference signature datacorresponding to a length of time of reference media content, forexample a number of reference signatures corresponding to 3 minutes ofreference media content. The query schemes for “immediate” search, the“+/−1” minute search and the “full” local search represent the ways andwhat segments of the signature cache are searched. As an example, threeminutes worth of reference signature data can be downloaded from theremote server by the client mobile media device, allowing for localreference database search as outlined in the previous sections. When anew set of signatures is downloaded, the contents of the signature cacheare overwritten. The size of the local memory signature cache isprogrammable. A full local search refers to searching through the entirelocal memory cache reference content to try to find a match. The fulllocal search is generally the last attempt to find a match to the queryin local memory. After the full local search, if the query not found, asearch of the remote reference database is initiated and if a match isfound at the remote database, a new chunk of reference material for thematch is downloaded overwriting the old chunk in the local memory.

Querying with audio content that is not in either the local or remotereference database will result in NOT FOUND at both the local and remotestages. Once the miss threshold1 has been reached and before a match isfound, queries will be sent to the remote server. This increases theload on the remote server without getting any of the caching benefits ofthe local search.

FIG. 7B illustrates a process 730 for controlling and limiting access toa remote server to prevent an increase in the network bandwidth for thecase of a query for nonexistent reference data in a remote referencedatabase. To resolve this case, another counter having a count value T3is introduced in FIG. 7B that keeps track of a count of how manyconsecutive NOT FOUND searches occurred to the remote server. FIG. 7Billustrates the utilization of this T3 counter in the overall process oflocal-remote switching mechanism. At step 732, media content iscaptured, fingerprinted, and local search is performed. If there is amatch at step 734, the next media query is initiated at step 732. Ifthere is no a match, a remote search is performed at step 736. If thereis a match in the remote reference database at step 738, a new chunk ofreference fingerprints is downloaded at step 740, and the process goesback to step 732. If there is no a match in the remote referencedatabase at step 738, the T3 counter is incremented at step 742. If anumber of consecutive remote search requests are executed with NOT FOUNDresults, bringing the T3 counter above a third threshold, threshold3, asdetermined at step 744, the next T4 queries to the remote server aresuppressed at step 746. The process 730 pauses at step 746 waiting forthe T4 requests to elapse. There is no need to stop capturing andquerying the local reference database since this does not have a largeaffect on performance or power drain on the mobile media device.However, going to the remote server involves transmitting queries and inthis case many queries when it is likely that the captured content isnot in the remote reference database. For example, while capturing andquerying a program, a long series of commercials begin to play and inthis example, these commercials are not in the remote referencedatabase. The transmitting of many queries would have an effect on thenetwork bandwidth utilization and performance of the remote server.Consequently, T4 queries are stopped providing time for the commercialsto end and the program to resume, for example. After these T4 queries,the process 730 resets the T3 counter, and returns to step 732 andanother query is searched locally and if not found sent to the remoteserver. If a query is found at any stage, then the appropriate countersare reset, a new chunk of reference fingerprints is downloaded at step740, and the process continues with step 732.

The record and identify application of step 406 in FIG. 4 performscapture media and query to the local and remote server. To allow forindependent start of media content capture and independent start offingerprinting and querying, the following functions are introduced:

-   -   1. startAudioCapture: This function starts the capture of audio        in the background. Audio samples are saved to a circular buffer.    -   2. stopAudioCapture: This function stops the capture of audio.    -   3. queryWithDuration: This function queries to the local and        remote search servers with a specified duration. For example, if        the duration is seven seconds, the audio samples in the buffer        corresponding to the previous seven seconds of content are        fingerprinted and queried. It is required to have started audio        capture before calling this function.        StartVideoCapture and stopVideoCapture functions are similarly        used for video media query support. Independent start of media        capture and independent start of fingerprinting and querying        allows the mobile media device to continuously capture media        content in the background, while simultaneously performing        fingerprinting and querying on the specified length of the media        content residing in the circular buffer.

For automatic switching between the local and remote search server, thesignature cache holds one set of signatures that is automaticallymanaged. That is, downloading and cache management are performedautomatically based on results of each search. FIGS. 6 and 7 address theflow of local and remote search processes using an automatic referencesignature download based on the outcome of a query search.

The signature cache can be also managed manually. A number of signatureslots may be specified when instantiating the system. Each signatureslot may hold multiple signatures. Manually managing the signature cacheis an advanced feature used in some application cases when a particularexpected captured media content is desired to trigger events within themobile media device. Additional functions are provided that allow foruser initiated or manual downloading of signatures from the remoteserver to particular cache slots, flushing the contents of the slot, andreturning a list of the manually downloaded reference signatures.Examples of these additional functions are given below:

-   -   1. initWithServerAndNumSlots: This function initializes the        content identification library, and sets it up for the        application use. The number of signature cache slots is        specified. This is an alternative to the initialization function        with predetermined parameters as described earlier in FIG. 4.    -   2. downloadSigsToCache: This function downloads signatures        associated with a particular program and specified by the        signature identification number (asset id) associated with each        signature to the specified signature cache slots. The contents,        if any, of the specified signature cache slot are overwritten.    -   3. flushSigsFromCache: This function removes signatures from the        specified signature cache slots.    -   4. getListOfCacheContents: This function returns a list of the        asset id, cache slot position, starting signature timestamp,        ending signature timestamp, and number of signatures for each        non-empty signature cache slot.

As described in the previous paragraphs, for the signature cache that isautomatically managed, if a match is found from the remote server,signatures are downloaded for a next specified chunk of time. As long asthe same content is being queried, and the local cache contains thedownloaded reference signatures, the local search will match with thesignatures in this automatically managed cache, keeping track of thetime line of matched reference signatures. However, after reaching theend of the time line in this signature cache, or the last matchingsignature in the current local cache, the local search will return NOTFOUND, and the query will eventually hit the remote server and again thesignatures will be downloaded for the next specified chunk of time.

However, before the end of the signature cache is reached, for instanceK seconds before the end, the next chunk of signatures may bepre-fetched or downloaded in advance prior to reaching the end of thesignature cache. Each signature is associated with a time stamp and thesuccession of signatures in a time line is known. Thus, before the lastsignature in the signature cache is reached, which would be the end of atime line for the locally stored chunk of signatures, a new chunk ofsignatures associated with the asset id and remaining time for the assetid is requested in advance of reaching the last signature. Thus, localsearch querying can continue uninterrupted.

The size of the chunk of signatures to download may advantageously beprogrammable, and specified by the function setSigDownloadChunkSize.This function specifies, in seconds for example, the size of the chunkof signature data to be downloaded at one time.

During reference signature download from the remote server, the localsearch database is locked only when copying downloaded signaturecontents into the database.

It is understood that other embodiments of the present invention willbecome readily apparent to those skilled in the art from the abovedetailed description, wherein various embodiments of the invention areshown and described by way of the illustrations. As will be realized,the invention is capable of other and different embodiments and itsseveral details are capable of modification in various other respects,all without departing from the present invention. Accordingly, thedrawings and detailed description are to be regarded as illustrative innature and not as restrictive.

We claim:
 1. A method for simultaneous capture and querying on a mobilemedia device, the method comprising: capturing a first fragment of mediacontent from a media presentation device during background operations ona mobile media device, wherein the captured first fragment of mediacontent is saved to a circular buffer; fingerprinting the first fragmentof captured media content retrieved from the circular buffer to generatesignatures representing the first fragment of captured media content;and querying a local reference database on the mobile media device withthe generated signatures while a second fragment of media content isbeing captured from the media presentation device.
 2. The method ofclaim 1, wherein the querying a local reference database furthercomprises: searching a first portion of the local reference databasethat limits searching to a portion of media content in the referencedatabase that is adjacent to a previous successful search match contentand slightly larger in time span than the current query length;searching a second portion of the local reference database that limitssearching to a time span content around the previous successful searchmatch content that is plus or minus N seconds, wherein for a selectedvalue of N the second portion of the local reference database is largerthan the first portion; and searching the local reference database as afull search of media content stored on the mobile media device.
 3. Themethod of claim 2, wherein the querying a local reference databasefurther comprises: transmitting the query to an external search serverupon finding no match situation on the mobile media device; searchingfor the query on the external search server; upon finding a match to thequery on the external search server, downloading a chunk of referencemedia content from the match and in an area surrounding the match to bestored in the local reference database on the mobile media device.
 4. Amethod for manual and automatic local signature cache management, themethod comprising: forming a signature cache on a mobile media device tohold one set of signatures that is automatically managed for switchingbetween a local search and a remote search, wherein downloading ofreference media signatures and signature cache management are performedautomatically based on search responses from the local search and fromthe remote search; and forming a manually managed signature cache withfunctions provided that allow for explicit downloading of the referencemedia signatures to the signature cache.
 5. The method of claim 4,wherein the signature cache is partitioned into a number of signaturecache slots, wherein each signature cache slot holds a plurality of thereference media signatures.
 6. The method of claim 4, wherein thereference media signatures to be downloaded are specified by assetidentification numbers and are downloaded to a specified signature cacheslot.
 7. The method of claim 4, wherein a list of the assetidentification numbers, slot index, starting signature timestamp, endingsignature timestamp, and number of signatures for each non-emptysignature cache slot are returned to the mobile media device.